Returns the actual keys of an object when possible, otherwise what keyof would return.
Basically if any key is set to a type like {[key:string]}, you won't get the individual keys. Also in this particular case with string you will get (string | number)[] (see keyofStringsOnly for why). You can avoid this by using a Record<string, string> or passing the second type parameter to narrow the type of the keys extracted.
Although it is not meant to be used with arrays, it can be, and will return number[] (even though technically it should be string[], but then typescript would complain).
Returns the actual keys of an object when possible, otherwise what keyof would return.
Basically if any key is set to a type like
{[key:string]}, you won't get the individual keys. Also in this particular case with string you will get(string | number)[](see keyofStringsOnly for why). You can avoid this by using aRecord<string, string>or passing the second type parameter to narrow the type of the keys extracted.Although it is not meant to be used with arrays, it can be, and will return
number[](even though technically it should bestring[], but then typescript would complain).